Effects of intensified silviculture on timber production and its economic profitability in boreal Norway spruce and Scots pine stands under changing climatic conditions

J Routa,A Kilpeläinen,V -P Ikonen,A Asikainen,A Venäläinen,H Peltola

doi:10.1093/forestry/cpz043

Abstract

Abstract The aim of this study was to examine how intensified silviculture affects timber production (sawlogs and pulpwood) and its economic profitability (net present value [NPV], with 2 per cent interest rate) based on forest ecosystem model simulations. The study was conducted on Norway spruce and Scots pine stands located on medium-fertile upland forest sites under middle boreal conditions in Finland, under current climate and minor climate change (the RCP2.6 forcing scenario). In intensified silviculture, improved regeneration materials were used, with 10–20 per cent higher growth than the unimproved materials, and/or nitrogen (N) fertilization of 150 kg ha−1, once or twice during a rotation of 50–70 years. Compared to the baseline management regime, the use of improved seedlings, alone or together with N fertilization, increased timber production by up to 26–28 per cent and the NPV by up to 32–60 per cent over rotation lengths of 60–70 years, regardless of tree species (although more in spruce) or climate applied. The use of improved seedlings affected timber yield and NPV more than N fertilization. Minor climate change also increased these outcomes in Scots pine, but not in Norway spruce.

Highlights

In Finland, the current target is to increase the annual domestic wood harvest by up to 80 million m3 yr−1 by 2030 in order to fulfil the increasing wood demand of the growing forest-based bioeconomy (The Finnish Bioeconomy Strategy, 2014)
The study was conducted on Norway spruce and Scots pine stands on medium-fertile upland forest sites under middle boreal conditions in Finland, under current climate and minor climate change
The use of improved regeneration materials alone, with 10 and 20 per cent higher growth rates (BG10 and BG20%), increased the timber yields by up to 12 per cent and 22 per cent during the rotation, compared to baseline management

Summary

Introduction

In Finland, the current target is to increase the annual domestic wood harvest by up to 80 million m3 yr−1 by 2030 in order to fulfil the increasing wood demand of the growing forest-based bioeconomy (The Finnish Bioeconomy Strategy, 2014). The annual wood harvest is still clearly lower than the total annual volume growth of Finnish forests (e.g. 107 million m3 yr−1 in 2018; Statistics, 2019), forest biomass production per unit land area should be increased to better meet the diverse and increasing targets set for the future forest-based bioeconomy. The lack of regeneration materials with high breeding gain still currently constrains its use in Finland, and especially in Norway spruce (Haapanen et al, 2016). The use of clonal material with high breeding gain in conifers is still limited in practical forestry due to the high cost and low availability of such seedlings (Högberg, 2003)

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